Frostline.info

Frost line depth in Whitley County, Kentucky

Frost reaches about 22 inches in typical soil across Whitley County. Codes in this climate commonly set footing depth at 18 to 30 inches.

Source: NOAA 100-year air freezing index (1951–80 station records) · Last reviewed

Moderate frost
Estimated frost depth
22″
typical silt/loam soil
Typical code footing depth
18–30″
rule of thumb for this climate
Design freezing index
499
°F-days, 100-year winter
ZIP codes covered
5
#99 of 120 counties in KY (1 = deepest)
22″ 0″12″24″36″48″ ground frozen
Est. frost (typical soil) Typical code footing depth Clay–sand range

Frost depth by soil type

Soil typeEst. frost depth
Sand / gravel (drains well)28″
Silt / loam (typical yard soil)22″
Clay (holds water)19″

County average. Methodology.

Verify before you dig. These are climate-based estimates. The legally required frost depth is the figure your building department publishes in its IRC Table R301.2 (climatic and geographic design criteria). Call the Whitley County building or permitting office in Kentucky and call 811 before digging.

Frost depth by ZIP code in Whitley County

ZIPCityEst. frostCode range
40701Corbin21″18–30″
40759Rockholds22″18–30″
40763Siler22″18–30″
40769Williamsburg22″18–30″
40940Frakes22″18–30″

What this means for your project in Whitley County

Deck footings & piers

Footings must bear below the frost line and at least 12″ below undisturbed ground. For planning in this area, budget for holes around 30″ deep until your permit office confirms the exact figure.

Fence posts

Set posts at least one-third of their above-ground height. Where frost heave is a problem, carry concrete footings below the frost line (about 22″ here in typical soil) and bell or taper the bottom.

Water & irrigation lines

Bury supply lines below the frost depth. Your water utility or plumbing code sets the minimum cover; add a margin below the estimate above for unusually cold winters.

Slabs & frost-protected foundations

Frost-protected shallow foundations (IRC R403.3) use the 100-year air freezing index — 499 °F-days here — to size perimeter insulation, letting footings sit shallower than the frost line.

Weather stations used

NOAA weather stationDistance100-yr AFI
Williamsburg 1 E, KY6 mi508
Barbourville, KY12 mi455
Middlesboro, KY21 mi550
Manchester 4 Se, KY30 mi404

Nearby counties

Common questions

What is the frost line depth in Whitley County?

About 22 inches in typical soil, based on NOAA's 100-year air freezing index. Across the county's ZIP codes the estimate runs from 21 to 22 inches.

How deep should footings be in Whitley County, Kentucky?

Codes in climates like this commonly require 18 to 30 inches. The Whitley County building department publishes the required frost depth in its adopted code (IRC Table R301.2).

Does frost depth vary within Whitley County?

Very little. Estimates across the county stay within 1 inches. Soil type matters more than location here.